Baseline dental examinations were conducted in October 1972, on approximately 2200 first through twelfth grade children in Nelson County, Virginia. All study participants in grades K-6 chew daily in school under supervision of the classroom teacher an acidulated phosphate-fluoride (APF) tablet containing 1 mg. F, rinse for 30 seconds with the resulting solution and then swallow the material. Once a week in school the same children also swish 10 milliliters of a 0.2 percent sodium fluoride solution for 60 seconds and then empty the contents of the mouth into a cup. A fluoride-containing dentifrice is distributed to the same children for use at home, and they receive toothbrushes periodically to take home. These combined preventive procedures will continue in the elementary schools for a minimum of ten years. Follow-up dental examinations are carried out biennially in all schools. Follow-up surveys were done in early fall of 1974, 1976 and 1978. Final examinations will be made in the Fall of 1982 when all senior high school students will have participated continuously in the elementary school program since entering first grade.